Anisotropy fields in excess of 120 KA/m (1500 Oe) have been produced in 3 nm to 5 nm thick polycrystalline films of Co by oblique sputtering of Ta underlayers. The unusually high anisotropy is magnetostatic in origin, and is induced by corrugations on the surface of an obliquely sputtered Ta underlayer. Cross-sectional TEM reveals 4 nm columnar grains of Ta tilted toward the Ta source and elongated perpendicular to the Ta flux in the film plane. The anisotropy field of the Co film increases with both the underlayer thickness and the angle between the Ta source and the film normal. In spin valve samples, the anisotropy is attenuated by more than an order of magnitude across a 4nm thick Cu spacer. Magnetoresistance measurements on a spin value indicate less than 2 dispersion in hard axis directions, and despite the nanometer-scale roughness of the underlayer, there is a weak broadening of the ferromagnetic resonance line.
Proceedings Title: Magnetic Materials, Structures and Processing for Information Storage, Symposium | | Magnetic Materials, Structures and Processing for Information Storage | Materials Research Society
Conference Dates: April 24-27, 2000
Conference Title: Materials Research Society Symposium Proceedings
Pub Type: Conferences
anisotropy, high Tc, magnetic coupling, Superconducting, susceptibility - ac